Iran's judiciary court has blocked the use of messaging app Telegram, according to state media.
The ban, effective as of Monday, relates to concerns of the popular service being used to coordinate illegal activity, according to the Islamic Republic News Agency, Iran's government-funded and controlled news agency.
Telegram was used by anti-government protestors during widespread unrest earlier this year. The country banned the use of the service during those protests, but only temporarily.
Telegram is considered to be the most popular messaging app in Iran. It is estimated that more than 40 million Iranians are signed up to the app. Iran has a population of more than 80 million.
Iran has been promoting a homegrown messaging app called Soroush instead. The app reportedly contains emojis that feature veiled women calling for "Death to America."
The Islamic country's clampdown comes hot on the heels of a move by Russia's communications regulator to bar domestic access to Telegram. The FSB, Russia's intelligence agency, had tried to gain access to Telegram's encryption keys but the company refused.
Russian entrepreneur Pavel Durov, Telegram's founder and CEO, has called for "digital resistance" to Russia's Telegram ban, in the belief that it will compromise Russians' human rights.
Internet censors in both countries are able to filter what websites and apps people can gain access to. To get around this, some use virtual private networks (VPNs) to access websites as if they are connecting to it from a different country.
Russians protested the Kremlin's move to block Telegram at a march in Moscow on Monday, in support of internet freedom and privacy.